1. Field of the Invention
The present invention pertains generally to medical devices. More particularly, the invention relates to devices for removing fluid from a predetermined area during surgery. The apparatus and methods provided by the invention are especially useful for microsurgery and nasal surgery.
2. Background Information
During surgery, unwanted fluids must be evacuated from the operating field. For large field surgery in the chest, abdomen or pelvis for example, this is often done by using a suction tube placed directly in pooled fluid such as blood. In microsurgery, however, because tissues affected are very small and delicate, use of direct suction even with a very small cannula and very low power can cause significant damage to, and even total destruction of, tissue exposed to the direct suction.
In large field surgery, fluid is also removed with sponges mounted on handles such as disclosed in U.S. Pat. No. 1,853,238 to Shields and U.S. Pat. No. 2,294,186 to Kirschbaum. Similar sponge sticks with hollow handles can be attached to a suction source as disclosed in U.S. Pat. Nos. 3,324,855 and 3,394,702 to Heimlich. All those devices are relatively large and designed to be grasped with a hand. They are not suitable for microsurgery where smaller workspace requires smaller tools, and quantities of fluid removed are smaller. Furthermore, to absorb liquids, those devices use gauze or elastomeric synthetic foam sponge for example. Because of their coarseness, these materials can damage delicate tissue typically involved in microsurgery when the materials contact these tissues. Therefore, these devices are not well suited for microsurgery.
To remove fluid during microsurgery, a small swab on a stick is often used. Swabs on a stick were disclosed in U.S. Pat. No. 3,179,108 to Block et at. Swabs used for microsurgery typically have an elongated triangular shape and are made of cellulose, for example. These are commonly called eye spears because the triangular shaped swab mounted on a 2" long shaft resembles a spear. A device sold under the trade name WECK-CEL is typical of those devices. Such a swab is small enough to be handled by the surgeon's fingers and fit in most areas of the body where microsurgery is performed. However, multiple swabs are needed to remove fluid in a typical microsurgery procedure since each swab quickly saturates and must be replaced. Besides using several swabs, the repeated removing of the saturated swab and replacing it with a dry one takes significant time and diverts the attention of the surgeon from the subject procedure, which is neither safe nor efficient.
Microsurgery presents another problem not typical in large field surgeries. Microsurgery is typically done on very small blood vessels, nerves, or other tissue which are delicate and often require a background mat or platform on which to rest these tissues during surgery. Prior art platforms or backgrounds often become basins that catch unwanted fluids, such as blood, which makes such surgery more difficult than if the platforms were clear of unwanted fluids. It is also not desirable to have to intermittently swab the platform during an operation to keep it clear of unwanted fluid.
U.S. Pat. No. 4,533,352 to Van Beek et at. discloses a flexible silicone rubber platform which incorporates suction in it. One embodiment of Van Beek's platform has a plurality of ribs and troughs with a hole in each trough connecting to a suction tube. The ribs support the tissue being worked on and the troughs allow fluid to flow in them to the hole where it is sucked away. In another embodiment, the tissues being worked on is supported by a porous pliable material. The porous pliable material has a synthetic coating on its bottom and sides.
Drawbacks of both of Van Beek's platforms include that they rely on gravity to conduct fluid to the suction holes. Therefore, they must be positioned so that fluid can move by gravity (rubber) or by direct suction (porous) to the holes. This significantly limits the positions in which the platforms can be used. Also, Van Beek's platforms have a rubber or plastic surface on the bottom which may be prone to becoming slippery when in contact with fluid, and which may allow the platform to slide on the tissue on which it is placed.
A further drawback of the Van Beek embodiment having a porous member with a synthetic coating on its edges is that the platform is not suited for trimming to fit a desired size or shape. Any trimming would remove a section of the coating on the edge which would allow the platform to "leak". While it is possible to recoat the edges after trimming, it is not practical to do so. An alternative but expensive solution is to make the platform in a great many predetermined geometrical shapes and sizes.
Another prior art platform is the TEBBETTS.TM. SOFT SUCTION MATT.TM. manufactured by Applied Medical Technology, Inc. That platform has a nonperforated membrane applied to a polyurethane foam pad which is approximately 1.5 mm thick. A suction tube having a plurality of holes is attached between the membrane and the foam pad. The TEBBETTS device is used with the membrane side down while the tissue being worked on rests on the foam.
A drawback of the TEBBETTS device is that it can be used in only limited orientations. Because the polyurethane foam has very poor wicking ability, the device only works by pooling fluids in the foam above the membrane. The polyurethane foam is open-cell and acts as a conduit for fluid to flow to the suction tube. The device can be shaped to allow such pooling, but it does not work well in orientations which do not allow gravity to drain fluid toward the suction tube.
Another drawback of the TEBBETTS device is that it slips. There is no mechanism to remove fluid which accumulates between the membrane and the tissue against which it is placed, so the device can slip on the accumulated fluid.
A further drawback of the TEBBETTS device is that it has no color. When blood pools in the foam pad, the pad turns red which makes it difficult to distinguish the tissue being worked on from the pad.
It is an object of the invention to provide a flexible sterile platform for use in surgery which removes excess fluid from its work surface by continuously and gently wicking fluid away into an integral pad where a suction tube subsequently removes it.
It is another object of the invention to provide a platform for use in surgery which removes fluid contacting its back side by gently wicking fluid into an integral pad where a suction tube subsequently removes it.
It is another object of the invention to provide a platform for use in surgery which can by oriented in any position.
It is another object of the invention to provide a platform for use in surgery which maintains a stable position and is slip-resistant on the tissue on which it is placed.
It is another object of the invention to provide a platform for use in surgery which is readily trimable to any desired size and shape.